The invention concerns a magnetic tape recording and playback device with a magnetic tape loading mechanism, in particular, a helical scan system as used in a video tape recorder and digital audio tape recorder.
In a conventional magnetic tape recording and playback device with a helical scan system, a rotating drum equipped with a magnetic head device that has rotating magnetic heads is for example installed on a mechanical chassis in a state coaxial with a fixed drum. A magnetic tape is made to run along the peripheries of these drums so that when the heads rotate at high speed, recording tracks are formed at an inclined angle on the tape. In this way, signals may be recorded or played back.
In such a magnetic tape recording and playback device, there is provided a loading mechanism which takes out the tape from a tape cassette, and winds it around the drums automatically. This loading mechanism comprises a loading block with tape guides, such as a return guide and an inclined guide which engage with and guide the magnetic tape.
The loading block may be driven by a rotating member such as a loading ring which rotates so as to bring the tape from the cassette to a specific loading position near the drums. The rotating member is driven by a motor and the position of loading block is detected by a switch.
This magnetic tape recording and playback device also has a pinch roller pressure mechanism which presses a pinch roller on a capstan. The pressure mechanism may comprises a pinch arm which is for example free to pivot on its one end, the other end thereof being fitted with the pinch roller, and the pinch roller being pressed to the capstan by the action of a solenoid or of a control motor and cam.
In this device, when the pinch roller is pressed against the capstan (i.e. when the pinch roller is ON), the magnetic tape runs at a constant rate, and when the pinch roller is released from the capstan (i.e. when the pinch roller is OFF), the magnetic tape can be moved in fast forward or rewind mode etc.
FIG. 3 shows a conventional example of magnetic tape recording and playback device disclosed in Patent Application Laid-Open No. 8755/1986. A mechanical chassis 1 is provided together with a rotating drum 2 and a pair of tape guides 3 which take out a magnetic tape and allow it to run smoothly. A loading mechanism drive motor 4 is provided together with pinch roller 5 and a pinch arm 6. A capstan 7 together with a pair of reel blocks 8 and a motor 9 which drives capstan 7 and reel blocks 8, and runs the tape are also provided. A deck mechanism 40 comprises all the above parts. An electric circuit 10 which drives and contrtols deck mechanism 40, and lead wires 11 provide an interface between deck mechanism 40 and electrical circuit 10.
In the conventional magnetic tape recording and playback device described above, deck mechanism 40 and electrical circuit 10 are separated, and lead wires 11 are therefore necessary to interconnect them. As there are from several tens to a hundred or so of these lead wires, a great deal of bothersome soldering and connections have to be carried out. The lead wires sometimes break and assembly work is therefore very slow. Furthermore, the fact that the deck mechanism and electrical circuit are separate from each other means that it is difficult to manipulate the device especially in manufacturing or repairing.
FIG. 7 is a perspective view of another conventional magnetic tape recording and playback device disclosed in Utility Model Application Laid-Open No. 34633/1986. A chasis 101 is provided together with a capstan 102 and pinch roller 103. A drive shaft 104, and a circular cam 105 are also provided. A lever 107 rotates on pivot 106, and a lever 109 rotates on pivot 108. A pinch arm rotates on pivot 108, and a spring 111 pulls lever 109 and pinch arm 110. A cam groove 112 is formed on circular cam 105, and a pin 113 is mounted on one end of lever 107 and moves in cam groove 112. A pin 114 mounted on the other end of lever 107. A slit 115 is formed on lever 109 and engagfes with pin 114, and a stopper 116 determines the positions of levers 109 and 110.
The operation of this device will be explained below. Cam 105 is rotated via a worm or other means by any drive mechanism, e.g. a motor not shown. Pin 113 moves along the side walls of cam groove 112, and lever 107 rotates on pivot 106. The rotation direction of lever 107 depends on the rotation direction of cam 105 and the shape of cam groove 112. Assuming that lever 107 rotates on pivot 106 in a clockwise direction, pin 114 then moves in slit 115 while maintaining contact with the side walls of the slit, which causes lever 109 to rotate in the anticlockwise direction under the action of moment on pivot 108. Spring 111 is then extended, pinch arm 110 is rotated in the anticlockwise direction on pivot 108, and pinch roller 103 which is attached on pinch arm 110 also rotates. When the angle of rotation reaches a specific value, pinch roller 103 comes into contact with capstan 102, and the extending force by spring 11 because of further rotation of lever 109 maintains pinch roller 103 in contact with capstan 102.
In the conventional magnetic tape recording and playback device described above, circular cam 105 is used. From a view of strength, the cam has to be made thick, and this makes it difficult to make the device thin. Also, the components of the device are arranged around circular cam 105, which leads to less freedom of design.
FIGS. 13 to 15 are diagrams showing the third conventional magnetic tape recording and playback device disclosed, for example, in Patent Application Laid-Open NO. 187151/1986. FIG. 13 is a plan view of an essential structure showing mainly parts fixed to an upper side of chassis, FIG. 14 is a plan view showing mainly parts fixed to a lower side of the chassis, and FIG. 15 is a longitudinal section in part of the device.
a chassis 201 is provided together with a reel wheel 202 fixed to chassis 201. A capstan supported 203a is supported rotatably on chassis 201, and a flywheel 203b is fixed to capstan 203a. A tape cassette 204 engages with reel wheels 202 and is located in a specific position on chassis 201. A magnetic tape 205 is wound in tape cassette 204, and a rotating drum 206 has magnetic heads and is mounted rotatably on chassis 201. Guide grooves 207 and 208 are formed on chassis 201. Tape loading blocks 209 and 210 respectively through guide grooves 207 and 208. A tension pin 211 is fixed to tension arm 212a which is supported rotatably on chassis 201. An extension spring 212b includes ends which are attached respectively to tension arm 212a and chassis 201. A pinch roller 213 is fitted rotatably on pinch arm 214a. Tape guides 215, 216 and 217 are installed on chassis 201.
Gears 218 and 219 are supported underneath chassis 201 for rotation. Arms 220 and 221 are fixed respectively to gears 218 and 219. Links 222 and 223 include one end of each being attached to arms 220 and 221 respectively such that they can rotate freely, and the other end thereof being attached to tape loading blocks 209 and 210 respectively such that they can rotate freely. A slider 24 slidably mounted underneath chassis 201. Slits 225 and 226 are formed on slider 224. Pins 227 and 228 are mounted on chassis 201 so that they pass through slits 225 and 226 respectively. A pressure member 229A engages with gears 218 and 219, and which like slider 224 has slits through which pins 227 and 228 pass. An extension 229B is spring attached to slider 224 and pressure member 229A. Racks 229a and 229b are formed on pressure member 229A. A guide groove 230 is formed on slider 224.
A circular cam 231 is supported rotatably underneath chassis 201. A cam groove 232 is formed on the bottom of cam 231, and a pin 233 is attached on arm 234 and engages with cam groove 232. Arm 234 is supported rotatably underneath chassis 201. A pin 235 is attached on arm 234, and 236 is a drive gear which is installed underneath chassis 201 and engages with cam 231.
Cam grooves 237 and 238 formed on the upper surface of circular cam 231. Pins 239 and 240 engage with cam grooves 237 and 238 respectively. Arms 241 and 242 include pins 239 and 240 which are attached respectively thereto. A spring 243 includes one end attached to pin 239; the other end, to pinch arm 214a.
An upper slider 244 is slidably mounted on the upper surface of chassis 201. A guide groove 245 is formed on upper slider 244. A pin 246 is fixed on arm 242 and engages with guide groove 245. A slit 247 is formed on upper slider 244. A 248 is fixed on chassis 201 and passes through slit 247. A slit 249 is formed on chassis 201. A pin 250 is attached on upper slider 244 and passes through slit 249. A pressure portion 251 formed on upper slider 244, and a hook 252 is formed on tension arm 212a.
The operation of this device will be explained below. In FIGS. 13 and 14, the elements shown by two-dot chain lines are in the 1st position where magnetic tape 205 has not been taken out from tape cassette 204, i.e. in the position of unloading. The elements shown by solid lines are in the 2nd position where magnetic tape 205 has been taken out from tape cassette 204 and brought into contact with rotating drum 206, i.e. in the position of loading.
In FIG. 14, the loading begins by starting a loading motor not shown. The motor torque is transmitted to drive gear 236, and cam 231 is rotated in the direction shown by arrow 299. Following this motion, arm 234 rotates in the direction shown by arrow 298, and lower slider 224 slides in the direction shown by arrow 297.
Since racks 229a, 229b formed on pressure member 229A engage with gears 218, 219 arms 220 and 221 rotate in the directions shown by arrows 296 and 295 respectively, and tape loading blocks 209 and 210 take out magnetic tape 205 from cassette 204 so as to bring it into the 2nd position where it is in contact with rotating drum 206. At this time tape loading blocks 209 and 210 move through guide grooves 207 and 208 respectively until they reach the loading position.
Simultaneously, the parts located on the upper surface of chassis 201 move as shown in FIG. 13. When cam 231 rotates in the direction of arrow 299, pin 240 slides along cam groove 238, arm 242 rotates in the direction of arrow 294, and upper slider 244 moves in the direction of arrow 293. At this time tension arm 212a, of which the rotation had been prevented by the contact of pressure portion 251 with hook 252, rotates until the tension in magnetic tape 205 balances that in extension spring 212b.
At the same time, pinch arm 214a rotates in the clockwise direction while maintaining contact with tape guide 217 which rotates under the driving force of another drive gear not shown in the figure. Pin 239 slides along cam groove 237, arm 241 rotates in the direction of arrow 292, and pinch roller 213 mounted on pinch arm 214a is pressed on capstan 203a in opposition to the force of compression spring 243.
When magnetic tape 205 is released from rotating drum 206, the loading motor not shown in the figure rotates in the reverse direction, and cam 231 rotates in the direction opposite to arrow 299. Following this motion, the levers, arms and sliders rotate or move in the directions opposite to the arrows and return to their original positions of unloading shown by the two-dot chain line, i.e. to the 1st position in which the magnetic tape is not taken out.
In the conventional magnetic tape recording and playback device of above construction, many cam grooves 232, 237 and 238 are formed on circular cam 231 which is needed to be installed in a limited space. As a result, the grooves have to be formed on both sides of the cam, and the cam must have a considerable thickness. Moreover, the moving amounts of pins 233, 239 and 240 which engage with the grooves of cam 231 are limited less than the radius of the cam. In order to drive the parts which have a great amount of movement, therefore, it is necessary to interpose other members between the parts and the cam. This means that the arrangement of parts is complex, and the device can not be made compact.
FIGS. 20 to 22 are drawings of the fourth conventional magnetic tape recording and playback device disclosed in Utility Model Application Laid-Open No. 166849/2985. FIG. 20 is a plan view of the device in a state of unloading, FIG. 21 is a plan view of the device in the half-loading position, and FIG. 22 is a plan view of the device in a state of loading. A chassis 301 is provided together with a rotating drum 302 installed at a specific inclined angle on chassis 301. A tape cassette 303 is positioned on chassis 301. Magnetic tape 306 is taken out from supply reel 304, and after being wound at a specific angle on rotating drum 302, is taken up by take-up reel 305. A capstan 307 is provided together with 308 and a guide groove 309 formed on chassis 301 for guiding pinch roller 308. A fixed head 310 is installed on chassis 301. A loading cam 314 driven by loading motor 311 via reducing gears 312 and 313. A cam lever 315 and a pin 316 are fixed on chassis 301. One end of cam lever 315 is supported rotatably by pin 316. A pin 317 is installed in the center portion of cam lever 315, and engages with a guide groove (not shown in the figure) formed on loading cam 314. A pin 318 is mounted at another end of cam lever 315. A spring 319 includes one end which is attached to pin 318; another end, to a connecting bar 320. A guide groove 302 is formed at one end of connecting bar 320, and engages pin 318. A pin 321 is attached at another end of connecting bar 320. A pinch arm 322 rotates on pin 323 fixed on chassis 301 and on which pin 321 is rotatably mounted. A guide post 314 is mounted on pinch arm 322 together with pinch roller 308. A pin 325 is attached at one end of connecting bar 326 and engages with pinch arm 322 such that it can rotate. A pin 327 is fitted at another end of connecting bar 326. A tape guide arm 328 rotates on a pin 329 fixed on chassis 301 and on which pin 327 is rotatably mounted. A tape guide post 328a is mounted on said tape guide arm 328.
Tape loading blocks 303 and 331 engage with ring gear 332 so as to wind magnetic tape 306 on rotating drum 302.
The operation of this device will be described below. First the loading operation in FIG. 20 is discussed. Loading motor 311 rotates in the clockwise direction, and this rotates loading cam 315 in the counterclockwise direction via reducing gears 312 and 313. Pin 317 attached on cam lever 315 slides along the side walls of the guide groove formed on said loading cam 314, so cam lever 315 pivots on pin 316 in the counterclockwise direction. Pin 318 fitted on cam lever 315 then moves connecting bar 320 via spring 319 in the direction of arrow A in the figure. Since connecting bar 320 is engaged with pinch arm 322 via pin 321, pinch arm 322 pivots on pin 323 in the clockwise direction. This causes both pinch roller 308 and guide post 324 mounted on pinch arm 322 to move in the loading direction.
As a result of the rotation of pinch arm 322, connection bar 326 moves via pin 325 in the direction of arrow B in the figure. As connecting bar 326 is engaged with tape guide arm 328 via pin 327, tape guide arm 328 is made to rotate on pin 329, and tape guide post 328a mounted on tape guide arm 328 is thereby loaded to a specific position. These operations bring the device to the half-loading position shown in FIG. 21.
In FIG. 22, ring gear 332 receives a driving force from a drive transmission mechanism (not shown in the figure) via a gear area on its outer circumference, and rotates in the clockwise direction. Tape loading blocks 330 and 331 which are engaged with ring gear 332 and situated inside of tape cassette 303 up to the half-loading position, then take out magnetic tape 306 and wind it on rotating drum 302 at a specific angle so as to reach the loading position shown in FIG. 22.
In the above conventional magnetic tape recording and playback device, tape guide arm 328 is located far from loading cam 314 which drives it, and the drive transmission mechanism from the cam to the arm therefore needs many components such as levers. As a result, it is difficult to ensure the precision of components or dimensional precision among many components, and the structure also takes up too much space.
FIG. 27 is a plan view of the fifth conventional magnetic tape recording and playback device in a state of tape-loading disclosed in Patent Application Laid-Open No. 36772/1987. A chassis 401 is provided together with a rotating drum 402 which is attached on chassis 401 and has magnetic heads. A magnetic tape 403 which is wound and moved around rotating drum 402. A tape cassette 404 is also provided in which tape 403 is stored by being wound around supply reel 405 and take-up reel 406. Tape loading blocks 407 and 408 have guide posts 409 to 412 for moving magnetic tape 403 smoothly, take out tape 403 from cassette 404 and wind it around rotating drum 402. Stoppers 413 and 414 are fixed on chassis 401 for stopping tape loading blocks 407 and 408 at specific positions after they load magnetic tape 403 around rotating drum 402. Guide grooves 415 and 416 are formed on chassis 401 for guiding movement of tape loading blocks 407 and 408. A capstan 417 is located at a take-up side of rotating drum 402 and a pinch roller 418 is provided for pressing magnetic tape 403 on capstan 417. A control head 419 and an erase head 420 each come into contact with loaded magnetic tape 403.
In the device described above, magnetic tape 403 is taken out from tape cassette 404 and wound around rotating drum 402 by guide posts 409 to 412 attached on tape loading blocks 407 and 408. After that, magnetic tape 403 is run by pinch roller 418 and capstan 417 rotating in a specific rate and the information is recorded to and played back from the magnetic tape running in a specific rate. At the time of unloading, tape loading blocks 407 and 408 move back along guide grooves 415 and 416 and magnetic tape 403 is stored in tape cassette 404.
Next the tape loading mechanism with tape loading blocks 407 and 408 will be described below.
FIG. 28 is a bottom view of the tape loading mechanism picked up from FIG. 27, and FIG. 29 is a cross section along the line 29--29 in FIG. 28. A gear 421 is provided to which a force generated from a driving source (not shown) for tape loading is transmitted. A cam gear 422 is provided on which a cam groove 423 is formed almost all around and which rotates in the left and right directions from one end of cam groove 423 to another. A rotating plate 424 is provided which rotates on pivot 425 and on which pin 426 engaging with cam groove 423 is fixed. Pin 426 moves along cam groove 423 in the radial direction of cam gear 422 in accordance with the rotation of the cam gear. Therefore rotating plate 424 rotates on pivot 425 in the left and right directions. Rotating plate 424 has gear portions 427 and 428 engaging with gears 429a and 430a which are fixed on oscillating member 429 and 430 rotating on pivots 431 and 432, respectively.
FIGS. 30 and 31 show in detail a driving mechanism comprising components from oscillating members 429 and 430 to tape loading blocks 407 and 408 in a state of tapeloading and tape-unloading, respectively.
Arms 433 and 434 are rotatable on pivots 431 and 432 and stop in a state of unloading at the positions where stoppers 437 and 438 fitted on arm 433 and 434 are pressed to engaging portions 439 and 440 formed on oscillating members 429 and 430 according to the force generated from springs 435 and 436 interposed between arms 433 and 434 and oscillating members 429 and 430, respectively. Arms 441 and 442 include one end connected rotatably to arms 433 and 434 through pivots 443 and 444, another end is connected rotatably to tape loading blocks 407 and 408 through pivots 445 and 446, respectively.
In the tape loading mechanism described above, in the state of unloading, magnetic tape 403 is inside of tape cassette 404 and tape loading blocks 407 and 408 are positioned as shown in FIG. 31. At the time of starting loading from this state, gear 421 is rotated by a driving source for tape loading, cam gear 422 rotates in the clockwise direction in FIG. 28, pin 426 moves from the periphery to the inside of cam gear 422 along cam groove 423, and rotating plate 424 rotates on pivot 425 in the clockwise direction. Therefore oscillating members 429 and 430 rotate in the counterclockwise and clockwise directions because gears 429a and 430a engaging with gear portions 427 and 428 rotate counterclockwise and clockwise directions respectively, and tape loading blocks 407 and 408 move along guide grooves 415 and 416.
Since oscillating members 429 and 430 are driven by further rotation of rotating plate 424 in the clockwise direction after tape loading blocks 407 and 408 come into contact with stoppers 413 and 414, tape loading blocks 407 and 408 are pressed to stoppers 413 and 414 by the force generated from extended springs 435 and 436.
In such a conventional magnetic tape recording and playback device, cam groove 423 is needed to be in such a depth that pin 426 does not separate from cam groove 423, and to be formed to the extent of almost 360 degrees. Accordingly because of a problem of strength, the bottom of cam groove 423 is necessary to be thick. Also, it is needed to make the moving distance of pin 426 long and the reduction ratio between gear portions 427 and 428 and oscillating members 429 and 430, large. This is disadvantageous to an achievement of a thin device.
FIGS. 34 and 35 are plan views of the sixth conventional magnetic tape recording and playback device in states of loading and unloading, respectively disclosed in Utility Model Application Laid-Open No. 105938/1986. A chassis 501 is provided with guide grooves 502 and 503 formed on chassis 501, and tape loading blocks 504 and 505. Stoppers 506 and 507 are provided for stopping tape loading blocks 504 and 505 at specific positions. A rotating drum 510 is provided together with a tension arm 511. A tension post 512 and a pin 513 attached on one end and another of tension arm 511, respectively. A pivot 514 is fixed on chassis 501 for supporting tension arm 511 rotatably. A spring 515 is provided for pulling tension arm 511 in the counterclockwise direction. Loading cam member 520 is driven by a motor (not shown). The first sliding lever 521 has slots 524 and 525 in which pins 522 and 523 attached on chassis 501 are inserted so that lever 521 can slide linearly on chassis 501. Lever 521 slides linearly in accordance with the rotation of loading cam member 520 because pin 526 fixed on lever 521 engages with a cam groove (not shown) formed on loading cam member 520. The second sliding lever 527 having rack 528 is mounted on lever 521 so as to be slidable. Pinch arm 529 having pinch roller 531 is supported rotatably on chassis 501 through pin 530. A gear portion 532 engages rack 528, and a capstan 533 is mounted on chassis 501. Arm 534 having pin 534a engaging with groove 536 formed on lever 521 is supported rotatably on chassis 501 through pin 535. A slidable lever 537 includes one end connected with arm 534 and another end includes a slot 539 in which pin 538 fixed on chassis 501 is inserted.
A transmission mechanism (not shown) is interposed between loading cam member 520 and tape loading blocks 504 and 505, so that tape loading blocks 504 and 505 can move according to rotation of loading cam member 520.
The operation will be described below. In the state of loading shown in FIG. 34, tape loading blocks 504 and 505 engage with stoppers 506 and 507, pinch roller 531 is pressed on capstan 533, and a magnetic tape (not shown) is loaded in a specific path so that information can be recorded and played back. At this time tension arm 511 is located in the loading position so as to be able to control a tension of magnetic tape.
When unloading is started, loading cam member 520 is rotated by a motor, and in accordance with the rotation, the first lever 521 moves in the direction of arrow A. Since gear portion 532 is engaging with rack 528, pinch arm 529 is rotated in the direction of arrow B. Arm 534 is rotated by engagement between pin 534a and groove 536, so lever 537 moves in the direction of arrow C. When end 537a of lever 537 engages with pin 513 attached on tension arm 511, tension arm 511 is rotated in the direction of arrow D. Also tape loading blocks 504 and 505 are moved in the directions of unloading by rotation of loading cam member 520 through transmission mechanism.
Rotation of loading cam member 520 achieves the unloading state as shown in FIG. 35, where tape loading blocks 504 and 505, and tension post 512 is located inside of tape cassette 508.
Loading operation will be described below. The operation is reverse to the unloading one. Namely, according to the rotation of a motor, tape loading blocks 504 and 505 move along guide grooves 502 and 503, and engage with stoppers 506 and 507, respectively. Also, the first lever 521, arm 534, and lever 537 move in the directions reverse to the unloading ones by the rotation of loading cam member 520. Since pulled by spring 515 in the counterclockwise direction, tension arm 511 is rotated in the counterclockwise direction while maintaining contact between pin 513 and end 537a of lever 537. When tension arm 511 reaches a specific position, end 537a is separated from pin 513, so that tension arm 511 can control a tape tension.
The conventional magnetic tape recording and playback device described above has the same problems as in the fourth conventional device.